The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Generally, computer numerical control (CNC) machines execute preprogrammed sequence of commands to automate various machining operations. For example, drills, lathes, and water jet cutters can be configured as CNC machines. A CNC machine typically includes multiple components such as a motor, spindle, ballscrew, rotary axes, and column, and may be operable to orientate a work piece relative to a tool attached to the spindle before machining the work piece. Each of these components have different thermal expansion properties and can cause the CNC machine to become out of position.
To properly position the tool with a work piece, the CNC machine is calibrated with a machine reference point (“reference point” hereinafter) that serves as the origin point of the coordinate system used by the CNC machine. The reference point may be determined using a probing routine that utilizes a precision gage bore, which can be positioned on a fixture, and a touch probe attached to the spindle. During machining, the temperature can fluctuate due to heat caused by, for example, motor, cutting energy, idle operation and friction. The fluctuation in temperature can lead to thermal growth of various components, such as the spindle, the ballscrew, the rotary axes, and the column, and cause the reference point to shift. For example, in minimum quantity lubrication (MQL) machining, where flood coolant is minimal, thermal growth can be up to 100 μm. In high-volume production, frequent starts and stops of a machine occur due to various reasons, such as a machine being blocked, starved, a gantry issue, and shift change, which can also move the reference point due to thermal growth.
These offset adjustment issues, among other issues related to the performance and cycle time of CNC machine, are addressed by the present disclosure.